Insight into low-temperature CH4 combustion over CeO2-Pd-MgAl2O4 catalysts by modulating metal-support interactions

The serial Pd/CeO2/MgAl2O4, CeO2/Pd/MgAl2O4, and Pd-CeO2/MgAl2O4 catalysts were successfully prepared for CH4 combustion, in which the deposition sequence of CeO2 and Pd was well regulated. Among these catalysts, the Pd/CeO2/MgAl2O4 showed the highest activity (T90 = 474 degrees C) and a low activation energy (62.2 kJ & sdot;mol- 1) for catalytic CH4 combustion. It revealed that the introduction of CeO2 and the change in loading order had little effect on the catalyst particle size and specific surface area. The superior performance should be attributed to the excellent low-temperature redox capacity, abundant surface oxygen species and Pd2+ species, which was originated from the different preparation strategy and metal-support interaction between Pd species and CeO2. Besides, the addition of CeO2 significantly increased the content of moderate and strong acidic groups on the catalyst surface, which reduced the SO2 adsorption capacity, leading to an improvement in the anti-SO2 poisoning ability. This study provides a reference for the rational design and regulation of catalyst structures.